HSK 7-9
函
hán名
envelope; case; letter
学校已向家长发出通知函。
Xué xiào yǐ xiàng jiā zhǎng fā chū tōng zhī hán.
The school has sent a notification letter to parents.
Say it
Hold the button, say it, then let go.
Also free:
Appears across levels (7-9) in the HSK 3.0 word list.